Positron emission tomography plays an important role these days in oncological diagnostics, for example. In FDG-PET (PET using fluorodeoxyglucose as the radiopharmaceutical) a particular advantage lies in the fact that information about a metabolic status of a lesion can be obtained with the aid of its sugar metabolism. However, a PET examination in the region of the intestine proves to be difficult for the following reasons:                Different types of tissue can be found in the intestinal region (essentially soft parts, fluid, air, bone) in the field of vision of the PET system, which makes calculating an attenuation correction more difficult. This applies in particular when a combined MR-PET device is used and no computed tomography data can be used for the attenuation correction.        The volume segment or section to be examined moves due to peristalsis during the examination. Image quality during the PET procedure deteriorates due to the in-motion unsharpness caused thereby and due to a long PET measurement time.        The intestinal wall is thinner than the resolution to be achieved by the PET system, as a result of which lesions are difficult to detect.        
It generally holds true for PET examinations that for any measured event only the line on which a “beta” or positron decay has occurred can be indicated. After being generated a positron also continues to move a short distance, which cannot be reconstructed from the measured values. In PET examinations, for that reason, only a probability distribution can ever be specified for the localization of an event. Added to this are a series of other error sources, such as a false coincidence, for example, which occurs when two photons not originating from the same decay arrive at the detector ring within the coincidence interval.